Aircraft landing gear are known for which the maneuvering between a deployed position and a retracted position is performed by means of an actuator of hydraulic type, for example a cylinder. Very often, the landing gear is left to lower under the effect of gravity, the cylinder being used as a regulator to limit the speed of lowering of the landing gear. To this end, the fluid expelled from the chamber of the cylinder is made to be drawn so that its volume is reduced in the lowering. This braking is automatic and therefore occurs even if the hydraulic generation were to fail, which represents a high level of safety.
Use is also made, notably on light aircraft, of rotary electromechanical actuators which cooperate with the landing gear either directly at the level of a pivot of the landing gear, or indirectly via a link rod coupled between a crank attached to the actuator and the caisson of the landing gear. Once again, the lowering of the landing gear takes place under the effect of gravity, and the electromechanical actuator is used as lowering regulator. To this end, the electric motor of the actuator is powered so that it exerts a resisting torque, thus regulating the speed of lowering of the landing gear.
However, in the event of an absence of power supply or of malfunctioning of the electric motor, there is no element of the motor that allows for braking and therefore controlling of the lowering of the landing gear, which can prove problematical since, in cases of uncontrolled lowering of the landing gear, there is a significant risk of damage to the latter when it reaches its end of travel.
To limit this risk, it is possible to envisage equipping the actuator with a number of electric motors so as to reduce the risk of failure of a motor of the actuator, but, doubling or tripling the number of motors needed to control the actuator would result in a considerable increase in the weight and the volume of the actuator. Moreover, the problem would still remain in the event of a general electrical failure.